MEMS gyroscopes have become an essential component in many consumer, industrial and automotive applications, owing to their small form factor and low production cost. However, their poor stability, also known as drift, has hindered their penetration into high-end tactical and navigation applications, where highly stable bias and scale factor are required over long periods of time to avoid significant positioning or heading errors. Improving the long-term stability of MEMS gyroscopes has created new challenges in the physical sensor design and fabrication, as well as the system architecture used to interface with the physical sensor. The development of effective self-calibration techniques would mark a significant step in that direction, because they would make it possible to maintain high accuracy in the sensors over time without the need for periodic off-line recalibration in specialized facilities.
Different solutions have been offered in recent years for the self-calibration problem, such as the phase-modulated (PM) gyroscope or frequency-modulated (FM) gyroscope, to provide self-calibration of scale factor to the gyroscope operation. However, most of these phase-based or frequency-based techniques fundamentally suffer from low signal-to-noise ratio caused by their relatively low sensitivity.
An efficient technique for calibration of the bias errors in axisymmetric gyroscopes used in recent years is mode-reversal. Although this technique can efficiently reduce the bias errors in an axisymmetric gyroscope, the post-processing puts a burden on its implementation. Moreover, the periodic reversal of the modes increases noise and reduces the operational bandwidth of the gyroscope. Furthermore, mode-reversal by itself cannot provide scale factor calibration capability.
Accordingly, a need exists for a system and technique in which a gyroscope, accelerometer, or other device may be self-calibrated without the need to physically rotate the device in order to determine an angular velocity of rotation for calibration purposes.